Mild sweating or swimming is often sufficient to remove most commercially available sunscreen formulations from a person's skin. The ease with which these sunscreens are washed off by water necessitates multiple applications to the skin. The need to repeatedly apply sunscreen is costly to the consumer, inconvenient and tends to cause consumers to delay reapplication of the sunscreen which may lead to sunburn. Since most sunscreen active agents are hydrophobic, one method attempted to overcome the problem of easy removal with water and to improve water resistivity of sunscreen formulations is to prepare water-in-oil or oil-in-water emulsions, however, products formed from these emulsions are aesthetically unpleasing and feel greasy or oily and heavy. In addition, surfactants, added to emulsions to reduce the surface tension between the hydrophobic and hydrophilic ingredients, unfortunately reduce the water resistivity of these formulations because surfactants (and other emulsifiers) facilitate the removal of sunscreen from the surface of the skin when it comes in contact with water. Thus, these emulsion-based formulations often include waterproofing agents, such as high molecular weight resins such as high molecular weight silicon fluids, to improve the water resistant properties of the sunscreen formulations. However, addition of waterproofing agents adds cost to the formulations and causes a deterioration of the product's aesthetic properties.
Accordingly, it is desirable to produce a stable surfactant-free formulation comprising an oil-in-water dispersion which is highly water resistant, maintains high levels of sunscreen protection, provides provide uniform skin coverage and is aesthetically pleasing, i.e., does not feel oily or greasy.